328 POWER OF THE SOIL TO ABSORB SALTS [chap. 



obtained by Deherain, who collected the drainage from 

 cement tanks 2 m. cube and systematically filled with 

 soil taken from corresponding depths in the field. The 

 soils had been several years in the tanks, so that they 

 had settled down into practically normal conditions, 

 though the effect of the aeration and disturbance of 

 the soil in filling the tanks is still visible in a rather 

 high rate of nitrification. Each tank carried the crop 

 indicated in the first column. 



The rainfall of the year in question, March 1896 to 

 March 1897, amounted to 28*8 inches, most of which 

 fell in the autumn. The most noteworthy results are 

 the effect of the various crops in diminishing the loss 

 of nitrates, which is not wholly to be attributed to the 

 quantity taken up by the crop, because the sum of the 

 nitrogen removed in the crop and that carried off in 

 the drainage water is never equal to the nitrogen 

 removed from the uncropped plots by the drainage 

 water alone. ' During the comparatively dry spring 

 months the crops leave so little moisture in the soil that 

 nitrification is checked, and the total production of 



